Bitumen recovery from oil sands presents technical and economic challenges due to high viscosity of the bitumen at reservoir conditions. The viscosity of the bitumen prevents the bitumen from flowing in a reservoir. Various stimulation approaches exist to make the bitumen mobile enough for production from a wellbore.
Steam assisted gravity drainage (SAGD) provides one process for producing the bitumen. During SAGD operations, steam introduced into the reservoir through a horizontal injector well transfers heat to the bitumen upon condensation. The bitumen with reduced viscosity due to this heating drains together with steam condensate and is recovered via a producer well disposed parallel and beneath the injector well. Residual bitumen remaining in the reservoir and costs associated with energy requirements for the SAGD operations restrict economic returns.
In situ combustion (ISC) also enables recovery of the bitumen but has returns reduced by expenses to establish fluid communication between wells. For ISC methods, an oxidant injected into the reservoir reacts with the bitumen once ignited to provide a source of heat for mobilizing the bitumen. Since heat, oxygen and fuel must remain available to sustain the reaction, combustion products and mobilized bitumen becoming trapped in the reservoir due to immobility of the bitumen can extinguish the ISC.
Therefore, a need exists for methods and systems for recovering hydrocarbons from oil sands with limited costs given total recovery obtained.